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November 30, 2011

Unhatched Turtles Communicate To Coordinate Hatching

by editor

Scientists believe that baby turtles have the ability to communicate with each other before hatching, and can arrange to emerge from their eggs at the same time.

Researchers from the University of Western Sydney said that Australia's Murray short-necked turtle embryos synchronized their hatching to prevent smaller turtles emerging alone and being attacked by predators like goannas and foxes.

They believe unhatched turtles may be able to sense each other's heart vibrations or may detect gases emitted from the breath of other turtles.

The team said that more developed turtles can send signals on their growth status to less developed ones to encourage them to increase their growth rates.

"I am pretty sure they're not sitting there chatting to each other but no one really knows," Dr Ricky Spencer, a co-author of the new study, said in a press release.

The team said that embryos positioned at the bottom of the nest have a "catch-up mechanism" that helps enable them to overcome their longer incubation periods.

Although the precise nature of the mechanism remains unknown, Spencer said that the eggs communicate through chemical clues.

"An egg is actually breathing. It's sucking in oxygen and expiring carbon dioxide," he said in a press release. "If you've got a lot of well developed eggs in the nest, there would be more CO2."

The buildup of CO2 in the nest could trigger under-developed embryonic turtles to increase their metabolic rate.

The team studied the turtles by dividing a clutch of eggs into two and incubating them at different temperature levels.

They then united the eggs after a week and analyzed their embryonic heart rates and metabolic rates.

The cooler embryos had sped up their heart rate and metabolism during the last third of the incubation period, and they also hatched within a couple days of the warmer ones.

Spencer said that coordinating hatching times makes sense from an evolutionary perspective, because otherwise it would leave the late-hatching turtles vulnerable to predators.

"If they don't hatch out with their siblings, they'll be sitting ducks," he said in a press release.